Our Waters GPC has 3 columns, an HT-4, HT-3, and HT-2, which cover the molecular weight range from 1,000,000 to 92 daltons. The solvent now being used in the system is THF. This instrument can be used in several different ways. One way is to do simple GPC work, in which retention time via size exclusion chromatography is related to molecular weight. For doing simple GPC work, we have a Waters UV detector (254 nm), and a Wyatt Optilab Refractive Index detector. The GPC is calibrated with a series of low dispersity polystyrene standards. We have Waters’ Millennium software for GPC data acquisition and processing.

Another way to use the system is to do light scattering measurements in conjunction with size exclusion chromatography. Data can be acquired and analyzed this way using Wyatt’s Astra software. Light scattering measurements can provide a true, absolute molecular weight, and also an estimate of the z-average molecular radius. However, you must know beforehand the value of the constant “dn/dc” in order to obtain molecular weight information from light scattering measurements.

The third way to use these instruments is to directly infuse sample solutions into the light scattering detector, using a syringe pump. With this method, you can use any solvent you wish, since the GPC chromatograph is not used.

Persons wishing to use the GPC chromatograph, or the Wyatt Light Scattering instrument, should contact Jim Windak, jwindak@umich.edu, for training.

You will need to provide an account number for billing your access time. The current rates are $9 per hour for UM shortcode accounts, and $65 per hour for non-UM accounts.

The GPC User’s Booklet (in Adobe pdf format) should be printed out and read prior to the GPC training session. It contains basic information about using the GPC, and using Waters’ Millennium software.

The Wyatt Light Scattering User’s Booklet should be printed out and read prior to training for the MiniDawn light scattering instrument. It contains basic information on setting up and using the instrument and the Astra software.

The GPC and Light Scattering Spectrometers are located in room 2069 Chemistry.